Sound generator



Sept. 1, 1959 A. H. BROOKS SOUND GENERATOR Filed Sept. 14, 1945 INVENTORARTHUR H. BROOKS BY L ATTORNEY 2,901,997 Patented Sept. 1, 1959 fficeSOUND GENERATOR Arthur H. Brooks, Cambridge, Mass., assignor to theUnited States of America as represented by the Secretary of the NavyApplication September 14, 1945, Serial No. 616,388

11 Claims. (Cl. 116-27) This invention relates to a sound generator andis illustrated herein as embodied in an underwater noise-making deviceadapted for use as a countermeasure against acoustically detonatedexplosive instruments, or the detection of a ship using the device byanother ship having underwater sound locating equipment.

Torpedoes and mines of the so called acoustic type have been designed toutilize the noise of a ships machinery or screw action to actuate theirdetonating devices. Moreover, owing to the effectiveness of water as asound conducting medium, the position of one ship from another havingunderwater sound locating equipment can be determined by the use ofeither listening or echoranging apparatus which is commonly embodied insuch equipment.

Noise making devices have commonly been mounted in ships ascountermeasures for detonating mines but such devices have an effectiveangular scope of limited extent and are usually directed forwardly ofthe ship only. Furthermore, any ship carrying an operating noisemaker isobviously a better target for the same reason.

In view of the foregoing, it is a principal object of the invention toprovide an improved sound generator for confusing the enemy when theship having the device is under detection, and for affording aneffective countermeasure against acoustic torpedoes which may approachthe ship from any direction, as well as against a listening or echoranging operation directed at the ship.

To this end, the invention provides a portable and expendible soundgenerator adapted to be dropped over the side of a ship from any partthereof and to produce sound or noise of such intensity as to mask thatof the ship, and any echo ranging sound impulses, the sound beingpropagated substantially uniformly in all directions. Accordingly, soundfrom the generator will detonate any torpedo that would be detonated bythe noise of the ship before the torpedo comes dangerously close to theship. Similarly, any echo ranging impulse reected by the ship will beobscured in the noise from the generator.

As `another feature of the invention, the sound generator has.associated therewith a float, from which the generator is suspended at adesirable level below the surface of the water until the generatorbecomes exhausted. During the period of its operation, the generator hasa substantially fixed position with respect to which a ship underdetection can maneuver in any suitable direction to take advantage ofthe masking or shielding effect of the generator, or the doubt createdon the enemy ship as to which source of noise is the real target.

In order tov avoid disclosing the position of the ship using thegenerator, the float is constructed and arranged slowly to lose itsbuoyancy so that by the time the sound from the generator ceases thefloat and generator will have started to sink to the bottom.

With these and other objects and features in view, the invention willnow be described with reference to the accompanying drawingswhichillustrate a preferred em- 2 bodiment of the invention and will bepointed out in the claims.

Fig. 1 is a side elevation of a sound generator embodying the invention,the float or container for the generator being shown in section.

Fig. 2 is a plan view of the left-hand part of thevgenerator shown inFig. 1. l

Fig'. 3 is a fragmentary elevation of the time-delay trigger mechanismfor actuating the supply valve.

Fig. 3A is a fragmentary sectional view taken along the line 3A-3A ofFig. 3 further illustrating the arrangement of the trigger mechanism foractuating the supply valve, and

Fig. 4 is a view in elevation showing the sound generator suspended inthe water by the float.

The illustrated sound generator comprises a oat or containerl which isadapted to house a sound generator unit 12, the float and unit beingconnected by a coiled line 14 about twenty-five feet in length. The unit12 comprises a resonator tank 16 having therein a supply of gas underhigh pressure. `Many kinds of gas can be used Vsatisfactorilyfbut CO2 isespecially suitable since it can be liquiied readily,l and `is availablein many places. The gas is delivered to an automatic gas operated hammer18, the striker 20 of which impinges rapidly upon an anvil 22 fixed tothe resonator tank. The hammer 18 may be of the conventional handriveting type which has a striking frequency of about blows per secondand which operates at a pressure of approximately 90 pounds per squareinch.

When the sound generator is to be used, the unit 12 is removed from thefloat through an opening in its lower end which is normally closed-by ahinged door 24 when the generator is stowed. The float 10 and unit 12are then dropped off the ship, whereupon the unit 12 sinks, pulls `theline 14 taut, and causes Vthe float to stand vertically inthe 'water asillustrated in Fig.V 4. This action of the unit 12 and float 10 occursso rapidly asto trap within the float practically all of the air whichlit contained "when dropped overboard. The upper end of the float 10 isclosed except for a small orifice 26 which allows-air to escape fromfloat 10Y slowly enough as to destroy the buoyancy of the float as soonas the gas in the resonator tank 16 has become exhausted.

The resonator tank 16 is composed of a cylindrical bodyhaving'hemispherical ends, the wall thickness of which is great enoughto withstand pressure in the neighborhood of 2,000 psi. The illustratedresonator tank has windings of piano wire 28 'soldered thereto which areintended to avoid any shrapnel effect which might result from the tanksbursting if hit by a projectile.- Fixed to the discharge end of the tank16 is a bracket 30 on which the hammer 18 is mounted close beside andparallel to the tank.

Gas is supplied from the tank 16 to the hammer 18 through well-knowncommercially manufactured connections comprising a supply valve 32 whichis xed on the discharge end of the tank 16, ya reducing valve 34, whichis to be adjusted in accordance with the requirements of the particularhammer used, and pipes 36 and 38 which connect the reducing valve withthe supply valve 32 and the hammer 18, respectively.

The stem 40 of the supply valve32 is normally urged outwardly into itsclosed position by the internal mechanism of the valve. ln order topermit the unit 12 and float-10 to become stabilized in the water asshown in Fig. 4, before the operation of the hammer 18 has started, altime delay device is provided for actuating the supply valve, Thisdevice comprises a trigger 42 which is pivoted on a stud 44 and isspring-loaded by a spring 46 having a suicient force stored therein tooperate the valve stem 40 when the trigger is released. The stud 44 ismounted on an `arm 48 which is fixed to the bracket 30, the arm having aflange 50 which provides an abutment for the upper end of the spring 46.

The trigger is normally heldcloseto, but-.out of engagement with, thevalve stem 40, by a cord 52 which is looped around the trigger and issecured to the flange 50. The cord is broken to release the, trigger byAa blasting cap 54 mounted on the arm 48 andconneeted `tooneend of a fuse5.6.- As shown in Fig. 3A the cord 52 isdisposed in close proximity withblasting can 54 whereby upon detonation of the c ap, ruptureofjthe cordis insured. The fuse is. securedlto the flangellr-by. a cord 5.8 and hasa lanyard 60 which whenpulled operates a standard blasting fuse igniterto ignite .the fuse 56. Thus, after ashort interval; (about 30seconds),- beginning with. the pulling7 of the lanyard, the fusesetsolff the cap 54 thereby initiating the operation of th'e hammer- 18.

The anvil Z2- is soldered to the mid-"portionV of-the resonator tank16at the side thereof. Various tests made with the anvil and hammer indifferent positions'with respect to the tank, indicate thesuperiority-of-the illustrated arrangement from the standpoints of bothvolume and directionalityv of the sound produced. As a result ofIinvestigating the directionality pattern of the illustrated soundgenerator, it hasbeen found to provide a substantially constantintensity of sound inf-alldirections with regard to a plane includingthe longitudinal axis of the tank as well as a plane perpendicular tothe axis of the tank.

The upper end'of the float is` tightly closed except for the restrictedorifice 26. This orice is made to close limits by soldering a tungstenwire, .010" in diameter, into -a larger hole in the tank near its upperend, and then withdrawing the wire to which the solder does not adhere.Near the lower end of the float and fixed thereto is a clip 62 to whichthe line 14 is attached, the other end of the line being tied around thedischarge end of the resonator tank 16.

The door 24 closely ts the lower end of the float-and is normally heldclosed by aspring hinge 64.

Exhaust holesy 59 in the hammer may be sealed watertight by a piece oftape whichis broken by the exhaust gases from the hammer as soon as itbegins to operate. A` similar temporary seal may be made between thestriker 20 and the body of the hammer.

Briefly to summarize the operation of the illustrated sound Igenerator,when occasion for its use arises, the unit 12 is removed from the oat 16and after the lanyard 6il-is pulled to ignite the fuseS6, the unit andfloat are dropped o'ver the side of the ship. The unit lzquickly sinksmaking the line 14 tautand hence righting the oat so -that itstandsvertically in the water as indicated'in Fig. 4. At this time theunit is suspended about 25 feet below the surface of the water andbegins to operate as soon as the fuse` 56 sets off the cap 54.

Owing to the weight of the unit 12 the air which is trapped in the floatis compressed somewhat and slowly discharges through the orifice '26.Consequently, the water rises slowly in the float throughout the periodof operation ofthe hammer. Eventually, when the gas supply in the tank16 is exhausted, the-buoyancy of the iloat is diminished to the pointwhere-it will no longer support the unit 12 andthen the float and unittogether sink to the bottom.

What is claimed is:

l. A soundv generator comprising a resonator tank adapted to holdcompressed gas, an anvil'ixed to said tank, a gasoperated hammerhaving ahighstriking frequencyy arranged to impinge on said-anvil connectionsbetween said container and-hammer for' supplying gas to the latter,saidconnections comprising a valve and a pressure reducing valve, aspring loaded trigger for opening said supply valve, means fory holdingsaid trigger in an inoperative position awaytfrom said valve andexplo-4g, sive means for releasing said last-mentioned means whereby saidsupply valve is opened by said trigger.

2. A sound generator comprising a resonator tank adapted to holdcompressed gas, an anvil fixed to said tank, a gas-operated hammerhaving a high striking frequency mounted on said tank and arranged toimpinge on said anvil, connections between said container and hammercomprising a supply valve and a pressure reducing valve, a springoperated trigger for operating said supply valve, means for releasablyholding said trigger away from said valve, said means comprising a fuseand cap constructed and arranged to free said trigger at the end of ashort interval after said fuse is ignited.

3. A sound generator comprising a resonator tank adapted to holdcompressed gas, a gas operated hammer having a high striking frequencysecured to said tank, an anvil fixed to said tank and arranged to besuccessively engaged by said hammer, connecting meansbetween said tankand said'hammer for supplying gas to the latter, a trigger mechanismoperable to permit ilow of gas from said tank to said hammer, andexplosive means for releasing said trigger mechanism.

4. A sound generator comprising a resonator tank adapted to holdcompressed gas, an anvil mounted on said tank at the mid-portionthereof, a gas operated hammer having a high striking frequency arrangedto successively impinge upon said anvil, connecting means including asupply valve between said tank and said hammer for supplying gas to thelatter, a spring loaded trigger for opening said supply valve, means forholding said trigger in an inoperative position away from said valve,and explosive means for releasing said last mentioned means whereby saidsupply valve is opened by said trigger.

5. A sound generator comprising a resonator tank adapted to holdcompressed gas, an anvil mounted on said tank at the mid-portion ofsaid'tank, a gas-operated hammer having a .high striking frequencyarranged to impinge on said anvil, connecting means including a shut-offvalve and a pressure-reducing valve between said tank vand said hammerfor supplying gas to the latter at the operating pressure of saidhammer, a spring loaded trigger for opening said shut-off valve, meansholding said trigger in its inoperative position, and explosive meansfor releasing said last-mentioned means after a predetermined intervalfrom an initial time whereby said shut-off valve is opened by saidtrigger.

6. A sound generator comprising, in combination, a cylindrical tankadapted to `hold `gas under pressure, an anvil secured to said tank, agas-operated hammer having a high striking frequency secured to saidtank and arranged successively to engage said anvil, and meansconnecting saidtank with saidhannner for supplying gas to said hammer atits operating pressure.

7. A sound generator comprising, in combination, a tank adapted to holda compressed gas, an anvil secured to the wall of said tanksubstantially equidistant the ends thereof, a ygas-operated hammerhaving a high striking frequency secured to said tank in substantiallyparallel relationship with said tank and arranged successively toimpinge on said anvil, and gas-conducting means connecting said tankwith said hammer for supplying gas to said hammer at its operatingpressure.

8. A sound generator comprising, in combination, a cylindrical tankadapted to hold gas under pressure, an anvil secured to said tank at themid-portion thereof, a gas-operated hammer having a high strikingfrequency secured to said tank and arranged successively to impinge onsaid anvil, said tank functioning as a resonator of sound'waves producedby the striking of said anvil by said hammer, gas-conducting meansincluding a shut-off valve connecting said tank with said hammer, andmeans for opening said shut-off valve after a predetermined intervalfrom an initial time.

9. Apparatus in accordance with claim 8 wherein said last-mentionedmeans comprises a'sprng loaded trigger normally held away from saidshut-0E valve, and explosive means for releasing said trigger to opensaid shut-off valve.

10. Apparatus in accordance with claim 8 wherein said last-mentionedmeans comprises a spring loaded 5 trigger normally held away from saidshut-oli valve by a cord, and a fused detonating cap positioned adjacentsaid cord for rupturing said cord and releasing said trigger to opensaid shut-off valve.

11. A sound generator comprising, a resonator tank 10 ing meansincluding a shut-off valve and a pressure re- 15 ducing "valveconnecting said tank with said hammer, a spring-loaded trigger foropening said shut-0E val-ve, a cord holding said trigger in aninoperative position away from said shut-o valve, and a detonating caphaving a fuse attached thereto mounted adjacent said cord for rupturingsaid cord at the end of a short interval after said fuse is ignitedthereby permitting the ow of gas ffrom said tank to said hammer.

References Cited in the le of this patent UNITED STATES PATENTS1,292,439 Dalen Jan. 28, 1919 1,496,746 Slichter June 3, 1924 1,611,740Haknemann Dec. 21, 1926 2,397,844 Dewhurst Apr. 2, 1946

